1. Field of the Invention
The present invention relates to a camber adjustment linkage for use with a vehicle independent suspension system so as to sense an improper wheel camber angle condition and to provide correction of such a condition by using vehicle jounce as the impetus for the correction.
2. Description of the Prior Art
Vehicle independent suspension systems are presently incorporated in production vehicles such as automobiles, trucks and vans, etc. Such suspension systems each support an associated wheel and tire for vertical up and down movement that is known as suspension jounce. On a level roadway, the angle between the center plane of the wheel and a vertical plane that extends through the wheel center point along the direction the wheel is directed is referred to as the wheel camber angle. When the center plane of the wheel is tilted inboard of the vertical plane at the lower side of the wheel, a positive wheel camber angle is present. A negative wheel camber angle is present when the center plane of the wheel is tipped outboard of the vertical plane at the lower side of the wheel. Maximum tire mileage is usually achieved when the wheel camber angle is zero degrees, i.e. the center plane of the wheel is oriented vertically.
U.S. production vehicles usually incorporate independent suspension systems only with the front wheels. However, some domestic vehicles do include rear independent suspension systems as well instead of the more conventional solid axle interconnection between the rear wheels. Foreign vehicles conventionally are manufactured with independent suspension systems for both the front and rear wheels.
Domestic and foreign independent suspension systems conventionally incorporate at least one control arm and a wheel supporting member mounted on the control arm. If the suspension system is for a front wheel, the wheel supporting member constitutes a steering knuckle which is movable angularly about a steering axis thereof to control the direction of vehicle travel. A wheel spindle constitutes the wheel supporting member if the independent suspension system is utilized with a rear wheel.
Usually, a pair of control arms are utilized with domestic independent suspension systems to mount the wheel supporting member. For example, the steering knuckle of a front independent suspension system will be supported on upper and lower control arms by upper and lower ball joints. Foreign independent suspension systems utilize a cylinder-like strut that cooperates with a single control arm to mount the wheel supporting member.
Wheel camber angle is conventionally measured by instruments which shine a light past the wheel onto a screen having indications that tell whether the camber angle is proper. The camber angle measurement by these conventional instruments is vehicle attitude sensitive. Normal camber angle change on conventional suspension systems is in the area of one half to one degree of change per inch of suspension travel. Consequently, domestic manufacturers generally specify a vehicle attitude or vehicle loading condition at which the camber angle must be checked or set to a designated amount. Conventional optical measurement equipment requires an accurately leveled base or platform from which to make measurements on the vehicle. The vehicle when placed on the base or platform must be in the correct attitude designated by the manufacturer and is sensitive to tire pressures, wheel run out, fuel and cargo loadings.
If the camber angle is not proper, adjustment is conventionally accomplished in one of two ways. The mounting of the suspension system on the sprung mass of the vehicle may include accomodations for shims whose thickness determines the camber angle. Thus, a positive or negative camber angle can be changed by adding thicker or thinner shims as required. Another way to adjust the camber angle is to have the components of the suspension system include a suitable threaded or eccentric interconnection that may be manually adjusted to provide correction of an improper wheel camber angle. The following U.S. Patents disclose various suspension systems having wheel camber adjustment generally of these types: U.S. Pat. Nos. 2,605,118; 2,664,297; 2,684,253; 2,900,196; 2,923,555; 3,033,588; 3,034,810; and 3,342,507.
Non-conventional vehicle independent suspension systems have also included load bearing components that function to maintain a proper wheel camber angle; see U.S. Pat. Nos. 3,479,050; 3,497,233; and 3,711,113. Additionally, U.S. Pat. No. 2,907,578 discloses a vehicle independent suspension system including a piston and cylinder whose retraction and extension automatically controls the camber angle of a wheel carried by this suspension system.